The thesis work is included in a research project developed in collaboration between Politecnico di Milano, University of Brescia and an industrial Partner regarding the theme of Energy Harvesting by mechanical vibration. The coordination of the project is carried out by Professors Raffaele Ardito and Alberto Corigliano of the Department of Civil and Environmental Engineering of the Politecnico di Milano. The thesis concerns an in-depth study of MEMS scale devices intended for the energy recovering from environmental mechanical vibrations and application in industrial contest. More in detail, typical resonant micro-energy harvesters with piezoelectric energy transduction mechanism are studied and modeled. The structural scheme used is a monomorph cantilever and a geometric volume for the device is fixed upstream of the study. In a first step, the upper bounds of the performance for different structural schemes are determined in terms of electrical power extraction under harmonic monochromatic oscillation of the support. This phase is carried out through a developed Matlab code which provides a computational approach in the frequency domain. The impact of various aspects on energy performance was also investigated: the use of an ideal or realistic stratification and its geometrical thickness, the effect of dielectric losses in alternating current and the use of different electrical load conditions. In addition, a tip mass has been optimized on technological and theoretical constraints to break down the high frequencies of the microsystem. A study on a bimorph plate is also proposed. In a second phase computational dynamic analyses are proposed in time domain, carried out with the ABAQUS finite element code. In this case, the performance evaluation is under other type of loads, such as an impulsive load and the presence of impacts between structural components of the device. The various results are also discussed and compared with ideas for the future pursuit of the work. In conclusion, at present, the solution with harmonic load at resonance frequency of the structure and the solution with impulsive load are competitive.
Il lavoro di tesi è inserito all’interno di un progetto di ricerca sviluppato in collaborazione fra il Politecnico di Milano, l’Università degli Studi di Brescia e un Partner industriale riguardo il tema dell’Energy Harvesting da vibrazione meccanica. Il coordinamento del progetto è svolto dai Professori Raffaele Ardito e Alberto Corigliano del Dipartimento di Ingegneria Civile ed Ambientale del Politecnico di Milano. La tesi riguarda uno studio approfondito di dispositivi alla scala MEMS destinati al recupero di energia vibrazionale da fonti ambientali per impiego in ambito industriale. Più in dettaglio, vengono studiati e modellati tipici micro-energy harvester risonanti con meccanismo di trasduzione piezoelettrica dell’energia. Lo schema strutturale utilizzato è una mensola monomorfa. Viene fissato a monte dello studio un volume geometrico per il dispositivo. In una prima fase vengono determinati i limiti superiori delle prestazioni di diversi schemi strutturali in termini di estrazione di potenza elettrica sotto oscillazione armonica monocromatica del supporto. Questa fase viene condotta attraverso uno strumento di calcolo automatizzato in Matlab che prevede un approccio computazionale nel dominio delle frequenze. Si è inoltre investigata l’incidenza di vari aspetti sulla prestazione energetica: l’utilizzo di una stratificazione ideale o realistica ed il suo spessore geometrico, l’effetto delle perdite dielettriche in corrente alternata, l’utilizzo di differenti condizioni di carico elettrico. Inoltre, è stata ottimizzata sui vincoli tecnologici e teorici, una massa di estremità per abbattere le alte frequenze del microsistema. Viene anche proposto uno studio su piastra bimorfa. In una seconda fase vengono proposte analisi dinamiche nel tempo, condotte con il codice ad elementi finiti ABAQUS per la valutazione delle prestazioni sotto altre forzanti quali, la forzante impulsiva e la presenza di urti tra componenti strutturali del dispositivo. Vengono inoltre discusse e paragonate le diverse prestazioni con spunti per il proseguimento del lavoro. Le soluzioni con forzante armonica a risonanza e con forzante impulsiva risultano tra loro competitive.
Microstrutture piezoelettriche per applicazione di energy harvesting in ambito industriale
ROSSO, MICHELE
2018/2019
Abstract
The thesis work is included in a research project developed in collaboration between Politecnico di Milano, University of Brescia and an industrial Partner regarding the theme of Energy Harvesting by mechanical vibration. The coordination of the project is carried out by Professors Raffaele Ardito and Alberto Corigliano of the Department of Civil and Environmental Engineering of the Politecnico di Milano. The thesis concerns an in-depth study of MEMS scale devices intended for the energy recovering from environmental mechanical vibrations and application in industrial contest. More in detail, typical resonant micro-energy harvesters with piezoelectric energy transduction mechanism are studied and modeled. The structural scheme used is a monomorph cantilever and a geometric volume for the device is fixed upstream of the study. In a first step, the upper bounds of the performance for different structural schemes are determined in terms of electrical power extraction under harmonic monochromatic oscillation of the support. This phase is carried out through a developed Matlab code which provides a computational approach in the frequency domain. The impact of various aspects on energy performance was also investigated: the use of an ideal or realistic stratification and its geometrical thickness, the effect of dielectric losses in alternating current and the use of different electrical load conditions. In addition, a tip mass has been optimized on technological and theoretical constraints to break down the high frequencies of the microsystem. A study on a bimorph plate is also proposed. In a second phase computational dynamic analyses are proposed in time domain, carried out with the ABAQUS finite element code. In this case, the performance evaluation is under other type of loads, such as an impulsive load and the presence of impacts between structural components of the device. The various results are also discussed and compared with ideas for the future pursuit of the work. In conclusion, at present, the solution with harmonic load at resonance frequency of the structure and the solution with impulsive load are competitive.| File | Dimensione | Formato | |
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2019_07_Rosso.pdf
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https://hdl.handle.net/10589/148782